The present invention relates to a device adapted to effect transmission of information signals e.g. analog signals, digital signals or digitalized data signals etc. between a plurality of units in a non-contact manner and with high precision by making use of a medium such as electromagnetic waves or light.
In machinery apparatus including a rotary or movable part e.g. stationary equipment, NC machine tools, robot apparatus or conveyer apparatus etc. constituted with combined plural sets of devices, there are instances where it is required to realize signal transmission between the movable part and a stationary part. In such cases, these machinery apparatuses are configured to provide an active module at one side e.g. a stationary side of the apparatus body and to provide a passive module at the other side e.g. a movable part, thereby to transmit power or information signals e.g. control signals etc. in a non-contact fashion from the active module to the passive module using electromagnetic wave or light, and to transmit various data signals such as information signals (e.g. indicative of shape, position, distortion, temperature or color etc.) in a non-contact fashion from the passive module to the active module. Further, integrated circuit cards of the contactless type which can be manufactured by applying the principle of the above-mentioned apparatus have good reliability as compared to integrated circuit cards of the contact type presently used. Accordingly, it is expected that a book made up by filing these cards can be substituted for conventional books as new media of information.
Hitherto, FM telemeters or wireless modems using electromagnetic wave or light as the transmission medium etc. have been used for these transmission devices of this kind. These devices all require a power source such as a battery on the transmission side. For this reason, when they are assembled into the mechanism of e.g. machine tools etc., it is required to provide the battery etc. with a care such that it is easily exchanged. Further, this is uneconomical in that the battery is apt to be dissipated to much extent. Moreover, since the weight of the battery is large as compared to that of the device body, much labor was needed for a dynamic balance when such a device is secured to a rotary body. Particularly, the employment of the FM telemeters etc. results in the complicated circuit configuration and high price. In addition, since the conventional integrated circuit cards are configured such that the transmission of data and power supply is effected through a contact, there is much possibility that failures such as bad contact will occur, resulting in lowering of the responsibility.